Emboldened by recent victories in Michigan and Indiana, last week Metcalfe joined five of his colleagues in the Assembly to reintroduce a bill that would limit the organizing power of unions in the Keystone State. It’s essentially the same bill he’s been trying to advance for the past 14 years, but Metcalfe thinks (rightly, perhaps) that the tides have finally turned in his favor; and he plans to strike while the iron is hot.

Regularly referred to under the catachrestic rubric of “right to work,” laws like Metcalfe’s have nothing to do with guaranteed employment. Instead they are designed to stifle union membership by prohibiting labor and management from enforcing so-called “agency shops”—workplaces that require workers to pay union dues as a prerequisite for employment. That means that new hires can piggyback on contracts and benefits they sacrificed nothing to gain. It also means that employees who are already represented by the union can stop paying their dues and ride on the coattails of those who do—at least until unions cease to exist, which they eventually will under such a regime.

Supporters of RTW claim that laws banning agency shops give an economic boost to the states that pass them, but any evidence that is the case is easily countered by examples where the opposite is true. The years following Oklahoma’s transition to a RTW state in 2001, for instance, witnessed declines in both manufacturing activity and employment; and despite predictions of an incoming surge of out-of-state businesses, the number of companies moving to Oklahoma actually declined.

On the other hand, some liberal commentators exaggerate the negative impact of “right-to-work,” arguing that such laws jeopardize things like overtime pay and workplace safety, both of which are largely regulated by federal law and already apply equally to both union and non-union employees (although evidence exists that unionized shops are a bit better at enforcing them than those with no representation).

Rhetoric aside, however, there is one universal effect of “right-to-work” legislation: Across the board, it has a negative impact on worker compensation. According to a study by the nonpartisan Congressional Research Service, workers in states that have banned agency shops make an average of $7,000 less than their counterparts in non-RTW states. The Economic Policy Institute, an opponent of right-to-work, determined that RTW leads to a three percent decrease in average hourly wages.

But, as the architects of these laws are well aware, the real impact of RTW is much more profound than that.

Even as a component of a wider pro-business platform, whatever tiny bounce the GOP may gain from supporting a ban on agency shops is, on its face, hardly worth the fight. Even Gov. Tom Corbett, who is no friend to labor, remains skeptical. After all, labor unions are already on life support in America. According to recently released statistics from the Bureau of Labor Statistics, union membership is at its lowest level since the 1930s. Today just 14.4 million workers—or 11.3 percent of the workforce—are represented. In the private sector it’s just 6.6 percent; and the number of new jobs that are unionized is hardly worth tallying.

By contrast, in 1983, during the height of the Reagan presidency, roughly 20 percent of U.S. workers were union members. And yet in the nearly three decades between then and last year only three states enacted RTW laws. It simply wasn’t a huge priority. So why all the urgency now?

You can thank Citizens United. The same ruling that opened the flood gates for corporate money into political campaigns lifted restrictions on union participation as well. In the past two national election cycles, in 2010 and 2012, organized labor has served as a massive progressive counterweight to the unchecked corporate power unleashed by the Supreme Court. In 2010, the public sector union The American Federation of State, County and Municipal Employees topped the list of all campaign contributors, spending nearly $90 million in an unsuccessful attempt to secure Democratic congressional supremacy. According to the Center for Responsive Politics, since 1990 organized labor has spent nearly $1 billion to influence elections; and more than 90 percent of union political contributions go to Democrats. (By law, dues-paying union members are not required to support these initiatives, and are only required to contribute their share of representation, collective bargaining and contract administration costs.)

By weakening unions, RTW doesn’t just hurt workers, it hurts progressivism, and anyone who benefits from it (which, by extension, includes anyone who benefits from Democratic policies: i.e. the poor, minorities, women, the disabled, the LGBT community, the environment … shall I keep going?)

Don’t be fooled: Right-to-work isn’t about pro-business Republicans and cigar-chomping capitalists milking a few more dollars from workers during labor negotiations. That’s just an added bonus. The real mission for the GOP is to take down the progressive money machine by emasculating its most prolific organizing base. I’d say that’s a battle worth fighting.